1. Field of the Invention.
This invention relates, generally, to sidewalk edging devices having laterally adjustable cutting blade members; more specifically, it relates to an edging device having means for adjusting the depth of the cut made by the laterally adjustable cutting blades.
2. Description of the Prior Art.
A sidewalk built in a grassy area will be gradually overgrown if the grass contiguous to the walk is not periodically trimmed. Wind and rain gradually shift soil and grass seeds over the edges of the walk and in a few growing seasons, a completely neglected walkway can become completely overgrown.
Accordingly, the edges of a well-maintained sidewalk are frequently trimmed. The trimming, most often referred to as edging, may be accomplished in numerous ways. The grass can be pulled by hand, cut with a hand-held trimmer, treated with grass killing chemicals, and the like, but these methods are time-consuming and impractical where substantial lengths of walkways must be maintained by just a few people.
A tool used by many individuals includes a small blade that rotates in a vertical plane; the blade is fixedly secured to the horizontally disposed output shaft of a motor. The rotating blade effectively trims the edges of the sidewalk, but the operator of the device must slowly and carefully guide the rotating blade down the extent of the walkway. Careless operation results in the rotating blade hitting and chipping the sidewalk.
Even these motor-operated edgers are inadequate to maintain miles of sidewalks. Accordingly, many municipalities use tractor-drawn edging devices that include a rotatably mounted disk-like blade member that simply rolls along the edge of the sidewalk and abrades vegetation growing thereover.
Although such devices are effective, they require two trips down the sidewalk, one pass for each edge thereof.
Examples of patents which show sidewalk edging devices and devices which could possibly be adapted to function as edgers are: U.S. Pat. Nos. 2,464,695; 3,093,196; 1,883,409; 4,404,918; 3,757,500 and U.K. Patent No. 2,119,213.
Some of these devices, again, could possibly be adapted to perform the function of walkway edging. However, many of them lack practical means for adjusting the distance between the blades.
Since sidewalk widths may vary, even within the same city, the ability of a device to adjust quickly to differing sidewalk widths is a most important feature. Although some prior art devices have some lateral adjustment capabilities, as aforesaid, the art of sidewalk edgers having easily adjustable blades has not heretofore reached its full fruition.
The devices of the prior art have still another important limitation; importantly, virtually no attempts have been made to overcome such limitation. The present inventors, therefore, are the first to even recognize the problem; their solution to the problem is thus a pioneering breakthrough in the art of dual-bladed sidewalk edging devices.
The present inventors have observed that the prior art devices do not take into consideration the fact that the condition of the soil and vegetation abutting the walk to be trimmed have a substantial impact on the edging procedure. Soft soil, for example, will abrade easily when trimmed with rolling disk members, whereas hard, dry soil will not. Moreover, vegetation that has been allowed to grow for substantial periods of time will offer substantially more resistance to the cutting blade.
Thus, a device which adequately performs its intended function when the soil is moist and reasonably soft and when the vegetation has not been allowed to grow for long periods of time may fail when the soil is dry and hard and when the vegetation has been allowed to grow, if the cutting blade members lack sufficient weight.
Nor is it acceptable to simply provide very heavy cutting blades, because such blades will sink too deeply into the soil when it is soft or when the vegetation is not established, thereby causing the tractor or other towing vehicle to use excessive amounts of fuel. Light blades should be used in soft soil or light vegetation to conserve fuel. However, light blades will simply roll over hard soil and thick vegetation and fail to adequately abrade the same.
One solution to the problem that has been perceived by the present inventors would simply be to maintain a supply of cutting blade members of differing weights and to change the blades to match the encountered soil and vegetation conditions.
However, that solution is cumbersome, time-consuming and inelegant.
The art neither teaches nor suggests a more acceptable solution to the problem of trimming vegetation having differing characteristics.